DYKDDDDK peptide is an eight-amino-acid (Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Lys) epitope tag used for protein purification and detection. It enables antibody-mediated purification via affinity chromatography, Western blot, and immunoprecipitation. The hydrophilic and immunogenic tag can be fused to either the N- or C-terminus of proteins.